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IMHO, any method of completing the game and any hero build is good, as long as it allows you to complete the campaign with that hero.
I was afraid to attack the island teeming with demons without a solid army. So, I started with something easier – mines and an abandoned castle.
I upgraded Faelan's attack, education, chaos, luck, and leadership.
I cheated a little at the start – I restarted the mission until Ossir appeared in the tavern, so I would have more archers.